Before last season, Zack Wheeler seemed like just another top pitching prospect who wasn’t going to work out. Wheeler had only pitched one full season between his debut in 2013 and 2017. Wheeler missed all of the 2015 and 2016 seasons while he was rehabbing from Tommy John. His return in 2017 wasn’t promising as his command issues worsened and hitters weren’t fooled by his offerings, and he allowed 15 homers in just 86 1/3 innings and ended the year with a DRA of 5.30.
His 2018, however, was quietly excellent. Wheeler started 29 games and pitched to a 3.31 ERA and a 3.01 DRA. His 4.1 fWAR was one tenth of a win behind his teammate Noah Syndergaard. Wheeler did a much better job keeping the ball in the ballpark, and it could be said that he was unlucky in 2017. He also cut down on walks and posted his best walk percentage at 7.4 percent. Meanwhile, he continued to miss bats and strike out roughly a batter an inning.
What’s interesting is that while Wheeler’s walk rate decreased, his ability to hit the strike zone stayed the same. Wheeler’s 49.2 zone percentage was two-tenths of a point off his career mark. What did change was Wheeler’s ability to get hitters to chase out of the zone. His 33.5 percent o-swing rate was four points higher than his career average and nearly ten points higher than his lost 2017.
The biggest change in approach was that Wheeler was one of many pitchers to drop the sinker from his repertoire. In 2017, Wheeler experimented with mixing the fourseam and sinker evenly. Prior to that, he had primarily thrown the fourseamer. The experiment wound up a failure. Throwing the sinker, Wheeler could hit the strike zone with regularity, but hitters rarely chased it or swung and missed at it.
The sinker also failed to do what sinkers are designed to do: induce ground balls. A 46.8 percent ground ball rate with a sinker is a bit pedestrian. Hitters mostly abused the pitch in 2017 as they slugged .598 against it. Knowing that the pitch had such poor results, it’s easy to see why Wheeler would want to abandon the pitch.
It’s a good thing that he did, because his fourseam fastball became so much more effective in 2018. Among qualified starters, Wheeler’s fastball was the sixth best in the majors by pitch value per 100 pitches. Previously, the pitch had been about average. The sinker wasn’t doing much to set up the fourseamer. What helped it play up was working more off his breaking and offspeed pitches especially his new addition: the split-finger.
The split finger helped Wheeler coax batters outside of the zone. Hitters went out of the zone for it 47.5 percent of the time in 2018. In other words, hitters chased it about as often as Javier Baez chases all pitches. Unsurprisingly, hitters had difficulty making contact with the pitch when it was thrown below the zone.
Wheeler’s adjustments should give him repeatable success in 2019. If the Mets are to contend in an increasingly competitive NL East, they’ll need him to duplicate last year’s resurgence.
Kenny Kelly is a writer for Beyond the Box Score and McCovey Chronicles. You can follow him on Twitter @KennyKellyWords.